What to wear for our ten year anniversary dinner?

I am wearing a nice dress-spaghetti straps, ivory trimmed in black, comes about to the knee. I don't know how my husband should dress. Is it okay for him to wear a polo with jeans or should he go a little more formal than that? He usually wears t-shirts and jeans. He says if I'm dressing up then he wants to do so as well, but I want him to be comfortable also. We are going to dinner at the restaurant that catered our reception. It's a steakhouse in Gatlinburg, TN, so we could get away with dressing casual or semi-formal. My main concern is that we are dressed in the same category, however, I am definitely wearing the dress!